Pyrophoric alloys with reduced iron content



United States Patent O" PYROPHORIC ALLOYS WITH REDUCED IRON CONTENT Walter Bungardt, Essen-Bredeney, Germany, 'assignor to Th. Goldschmidt A.G., Essen, Germany No Drawing. Filed Dec. 12, 1956, Ser. No. 627,740

Claims. (Cl. 75-152) This invention relates to the production of alloys and more particularly to products made from such alloys, such as flint rods from cerium(mischmetal)-iron alloys containing about or less than 15% iron.

It is a general object of the invention to provide means facilitating the production of pyrophoric alloys with an iron content greatly reduced in comparison with known alloys for flint rods used for pocket lighters, gas lighters and similar usages.

A more particular object of the invention is to provide means leading to a very efficacious production of cerium- (mischmetal)-iron alloys which are characterized by greatly simplified melting and forming procedure, and by a comparatively high pyrophoric power when compared with conventional cerium(mischmetal)-iron alloys containing considerably more than and far above 15% by weight of iron.

A more specific object of the invention is to provide means affording a great reduction in the burning off of certain ingredients of the pyrophoric alloy as it contains less iron than heretofore known cerium(mischmetal)- iron alloys, by the addition of magnesium, zinc, silicon, and antimony whose total percentage preferably does not exceed the total percentage of iron content of the alloy.

The invention accordingly contemplates the employment of preferred ingredients appropriately selected and formed to ingots, which ingredients were not used heretofore in the production of flint rods from cerium(mischmetal) -iron alloys consisting of less than 30% by weight of iron.

It is a known fact that the intensity of the pyrophoric properties of such alloys depends upon the amount of iron added to the combination of elements. Any increase in the iron content of the alloys increases their pyrophorosity; however, an iron content of about 30% constitutes the maximum of pyrophoric power obtainable for cast alloys.

The production of binary cerium(mischmetal) -iron alloys with high iron content of 30% necessitates, however, relatively high melting and casting temperatures. For instance, a cerium(mischmetal)-iron alloy containing 30% by weight of iron, can only be completely melted at a temperature above 1060 C.

Working with such high temperatures ensues the disadvantage of considerable losses through burning or firing off during the manufacture of cast flint rods, which losses are, of course, economically undesirable.

Therefore, many attempts were made to reduce the temperatures for melting and casting of such pyrophoric alloys, whereby, in the first place, a reduction of the iron content of the alloys was considered. This latter measure proved quite effective. For instance, a cerium(mischmetal)-iron alloy containing 20% by weight of iron brought down the melting point to 960 C. and an alloy with only of iron even reduced its melting point to about 800 C.

2,950,190 Patented Aug. 23, 1960 ice However, since the reduction of the percentage of iron in the alloy ensues simultaneously a loss of pyrophoric power, the present invention contemplates to take certain measures to overcome such disadvantages. The following table shows variou s combinations of ingredients resulting in an alloy capable of compensating for the loss of pyrophoric power:

This table contains some typical examples of alloys well known in the art. It is characteristic for these alloys employed in the manufacture of cast flint rods that their iron content has been reduced to but still above 15% averagely, whereby as compensation for losses of pyrophorosity the elements copper, zinc, silicon, magnesium and tin were employed in varying percentages and combinations.

Developments heretofore accomplished have shown that it is impossible to omit the addition of iron completely; practically seen, the reduction of the iron con tent in cast flint rods may be lowered to within about 15% by weight.

It has, however, been observed that 'a further replacement of iron by special alloy combinations results in losses of pyrophoric power of the alloy to such an extent that the amount of pyrophorosity of known binary cerium(mischmetal)-iron alloys, for instance with an iron content of 30%, cannot be obtained any more.

Further developments in the production of extruded flint rods have surprisingly shown that the pyrophorosity of cerium(mischmetal)-iron alloys containing only 8% to 15% of iron is of the same intensity as compared with binary alloys having about 30% by weight of iron, if as a compensation for the reduced iron content special combinations of alloys are employed which have not been used heretofore.

The following Table 2 shows some possible examples of alloys within the scope of this invention:

Table 2 No. Fe, Mg, Zn, Si, Sb, Bi,

percent percent percent percent percent percent This aforesaid table shows cerium(mischmetal) alloys with an average content of iron of 12.5% to which, as compensation for the reduced iron content below 15%, combinations of ingredients have been added such as magnesium, zinc, silicon, and antimony, whereby the total amount of these alloy ingredients or additions may not exceed the total percentage of iron contained in the ingot to be extruded. It would be advantageous to select the contents of antimony to range from about 1% to about 3% by weight.

Another possibility is to use in an alloy aside from the ingredients of iron, magnesium, zinc and silicon, and antimony combined; however, also in this latter instance, antimony preferably not exceeding 3%. It is also possible to change the ingredients, namely, iron, magnesium, zinc, silicium, and antimony in regard to their percentage or by further additions of elementsy however, the efiect and result of the pyrophoric material above indicated 'was not attainable.

' The following table illustrates the degree of pyroph oric quality- (sparking capacity) of flints manufactured through extrusion when employing the above stated alloys suitable in pocketlighters:

From the aforesaid table it en ues that the losses in pyrophorosity by the reduction 'of the iron content of the alloy. may be completely compensated for by compounded materials as hereinabove' stated. These com pounds or alloys show' for all practical purposes the important advantage that on account of facile'melting and forming conditions due to the decreased losses in .burning ofiof ingredients the same pyrophoric power 4 occur to persons skilled in the art without constituting a departure from the spirit and scope of the invention as defined, in the objects and in the appended claims.

Having thus described the invention, what isclaimed as new and desired to be secured by Letters Patent is:

1. A pyrophoric alloy for use in flint rod extrusion comprising about 10 to 12.8% by weight of iron, about 3.1 to 2.1% by weight of magnesium, about 0.8'to 1.2% by weight of zinc, between 0.1 to 0.4% by weight of silicon and between 1 to 3% by weight of antimony, the

V remainder being mischmetal.

2. An extrudable pyrophoric alloy comprising about 11.7 by weight of iron, about 2.5% by weight of magnesium, about 0.9 by weight of zinc, about 0.4% by weight of silicon and about 2.4% by Weight of antimony, the remainder being mischmetal;

3.,An extrudable pyrophoric alloy comprising about 10.0% byweight' of iron, about 3.1% by weightfof magnesium, about 1.2%1byweight of zinc, about 0.1% by weight of silicon and about,2'.8 by 'weight of antimony, the remainder being mischmetal.

4. An 'extrudable pyrophoric alloy comprising about 12.3 by weight of iron, about 2.2% by weight of magnesium, about 1;0% byjweight of zinc,*about 0.1% by may be achieved as was heretofore known only for cerium- (mischmetalyironalloys which had a relatively high iron 7 content of more than 15%.

It can thus be seen that there has been provided in the aforesaid invention a process and product arrived therefrom, which process contemplates the production of gan ingotfor the extrusion of aflint rod by adding to a cerium(mischmetal). alloy containing about 8% to 15% by weight of iron substantial traces of magnesium, zinc, silicon, and antimony, the total percentage of said'traces being at the most that of iron, the addition of antimony amounting to, approximately, but less than 3% by Weight.

Although specific embodiments of the invention have been described, it should be noted that the invention may be realized in modified form and adaptations of the arrangements herein disclosed may be made, as may readily weight of silicon and about 1.6% by weight of antimony, the remainder being mischmetal.

5. An extrudable pyrophoric alloy comprising about 12.8% by weight of iron, about 2.1% by weight of magnesium, about 0.8% by weight of zinc, about 0.1% by weight of silicon and about'2.2% by weight of antimony, the remainder being mischmetal.

References tilted in the file of this patent UNITED STATES PATENTS V r 1,023,661 Krieger Apr. '16, 1912 2,660,301 Bungardt Nov. 24, 1 953 7 2,792,301 Bungardt May 14, 1957 FOREIGN PATENTS 7 15,507 reat Britain f 1910 161,356 Australia Jan. 25, 1951 224,191 Germany July 9,.19-1'0 254,512

Germany Dec. 5, 1912 

1. A PYROPHORIC ALLOY FOR USE IN FLINT ROD EXTRUSION COMPRISING ABOUT 10 TO 12.8% BY WEIGHT OF IRON, ABOUT 3.1 TO 2.1% BY WEIGHT OF MAGNESIUM, ABOUT 0.8 TO 1.2% BY WEIGHT OF ZINC, BETWEEN 0.1 TO 0.4% BY WEIGHT OF SILICON AND BETWEEN 1 TO 3% BY WEIGHT OF ANTIMONY, THE REMAINDER BEING MISCHMETAL. 